Photographic emulsion



NOV. 26, 1946. E KNOTT- 2,411,546

PHOTQGRAPHIG EMULSION Filed April 12, 1945 lbdl de FIG. I.

FIG.4.

FIG.5.

EDWARD B; KNOTT A'I'I' 3 Patented Nov. 26, 1946 UNITED IVSTATE PATENT OFFICE PHOTO GRAPHIC EMULSION Edward B. Knott, Wealdstone, England, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application April 12, 1945, Serial No, 587,916

In Great Britain May 18, 1944 17 Claims.

spectrally sensitized emulsions can also be effected y inco p rating certain substantially, colorless heterocyclic bases, vizl those containing an amino group, in the spectrallysensitized emulsions (see United States Patent "2,177,635, dated October 31, 1939), Supersensitizationdifiers from hypersensitization which involves bathin of finished plates or films, an operation which normally reduces the pAg and/increases the pH of the emulsions with consequent decreased stability. v

I have now found a new method for supersensi tizing spectra-11y sensitized emulsions, which not only does not reduce the stability of theemul-v sions, but is valuable as a means of securing spectrally sensitized emulsions of increased speed.

It is, accordingly, an object of my invention to provide new supersensitized photographic emulsions. A further object is to provide a process for preparing such emulsions. Still other objects will become apparent hereinafter.

In accordance with my invention, a photographic silver halide emulsion spectrally sensitized with a 2"-cyanine dye or an oxacarbocyanine dye is supersensitized by incorporating in the emulsion at least one heterocyclic baseselected from those represented by the following general formula: a

wherein R1 and R2 each represents an alkyl group and Z represents a h'ydrazono group, an alkylhydrazono group, a 'dialkylhydrazono group, an

aralkylhydrazono group, a diaralkylhydrazono roup, an arylhydrazono group, a diarylhydrazono group, a hydroximino group, a earbamylhydrazono group, a thiocarbamylhydrazono group and a guanylhydrazcno group.

The compounds which I incorporate in the spectrally sensitized emulsion include hydrazones, semicarbazones, thiosemicarbazones, oximes and aminoguanides. Typical examples of these com pounds include:

4-hydroxy 3'-acetyl-2-methylnaphtha -1',2',4,5-

thiazole phenylhydrazone having the formula:

O5H5HNN- 0113 2CCH 4-hydroxy-3-acetyl-2-methylnaphtha -l,2',4,5- thiazole semicarbazone. f 4' hydroXy-3 acetyl-2-methylnaphtha -1,2',4,5-

a thiazole aminoguanide. I 4" hydroxy-3-acety12-methylnaphtha- 1,2,4,5-

thiazole ox'ime'. 4'-hydroxy-3'-acetyl2-methylnaphtha- 1,-2' ,l,5-

thiazole 'thiosemicarbazone. 1

I The sensitizing dyes which I employ in prace ticing my invention fall within the classof 2'- cyanine dyes and the class of oxacarbocyanine dyes. The supersensitizing efiects obtained with the 2cyanine dyes (especially the 1,1'-dialkyl- 2,2-cyanine salts) are much more marked than the effects which can be obtained with theoxacarbocyanine dyes. By the term Z cyanine dye, I mean a monomethinecyanine dye containing a quinoline nucleus linked through its '04- Or 2-position to another heterocyclic nucleus through the aor Z-position of the second heterocyclic nucleus. 'By the term oxacarbocyanine dyes, I mean a carbocyanine dye containing two benzoxazole nuclei. Among the 2'-cyanine dyes and oxacarbocyanine dyes which I employ in practicing my invention are the following:

1,1-dialkyl-2,2"cyanine salts, e. g., 1,1-diethyl- 2,2-cyanine halides, such asjthe iodide. 3,1'-dialkylbenzothia-2-cyanine salts, e. g., 3-

methyL-l'-ethylbenzothia-2f 7 cyanine halides, such as the bromide. 3,1-dialkylthia-2' cyanine salts, e. g., 3-methyl- 1-ethy1thia-2'-cyanine halides, such as the iodide. 3,1-dialkylselena-2'-cyanine salts, e. g., 3,l-diethylselena-z cyanine halides, such as the iodide. I 3,3-dialkyloxacarbocyanine salts, e. g., 3,3'-diethy1 or 3,3',9-triethyl oxacarbocyanine halides, such as the iodide.

The sensitizing dyes can be employed in any desired condensation. Ordinarily from to 30 mg. of dye per liter of emulsion (containing about 0.25 gram-mole of silver halide) will sufflee to produce the optimum sensitizing efiect. The methods of incorporating sensitizing dyes 1n emulsions are well known to those skilled in the art. Ordinarily, it is preferable to dissolve the dye in a water-miscible solvent, such asmethanol, and incorporating the methyl alcoholic solution in the emulsion. Ethyl alcohol or acetone may be employed instead of methanol. One or" more sensitizing dyes can be employed.

Ordinarily, the heterocyclic base is incorporated in the emulsion which already contains the sensitizing dye or dyes. However, the heterocyclic base can be incorporated in the emulsion before the sensitizing dye or dyes, or the heterocyclic base and the sensitizing dye or dyes can be incorporated in the emulsion simultaneously. Usually the heterocyclic bases are incorporated in the emulsion in a concentration equal to from about 10 to about 303 mg. for thatquantity of silver halide emulsion equivalent to 200 grams of silver nitrate. The optimum concentration for process-type emulsions is usually of the order of 100 mg. for that quantity of silver halide emulsion equivalent to 200 grams of silver nitrate. The heterocyclic bases are preferably but not necessarily dissolved in a water-miscible solvent, such as methanol before incorporation in the emulsion. One or more of the heterocyclic bases can be employed and the heterocyclic bases as well as the sensitizing dyes can be added to the emulsion during any suitable stage of its preparation. Usually both the heterocyclic bases and the supersensitizing dyes are advantageously added to the washed, finished emulsions.

To determine the optimum concentration of any of the heterocyclic bases, a batch of emulsion is first sensitized with the sensitizing dye in such quantity as to give optimum speed. Another batch of the same emulsion is similarly sensitized and several portions of this batch of emulsion a e treated with various concentrations of the heterocyclic base. Each of the portions of emulsion is then coated and exposed and processed as usual. The increase in the minus blue speed of the emulsion at optimum supersensitizer concentration is taken as a measure of the supersensitizing action of the compound. Wedge spectrograms also indicate this measure.

The accompanying drawing shows diagrammatically the spectrograms of emulsions containing sensitizing dyes with and Without the heterocyclic bases of the present invention. The com- Example 1 A gelatino-silver-bromiodide developing-out emulsion was sensitized with 1,l'diethy1 cyanine iodide having the formula:

C2115 C2H5 I trate. The sensitizing efiect of this quantity of dye is depicted in Fig. 1 of the accompanying drawing.

I Example 2 I To a gelatino-silver-bromiodide d e p emulsion, dye-sensitized as in Example 1, was added 4 hydroxy 3 acetyl 2 methylnaphtha- 1,2,4,5thiazole semicarbazone in a concentration of mg. per that quantity of emulsion equivalent to 200 grams of silver nitrate. The resulting emulsion showed an increase in green sensitivity of 500 per cent over the green sensitivity of Example 1. This increase in green sensitivity is apparent from Fig. 2 of the accompanying drawing which depicts the sensitivity of the instant emulsion.

Example 3 To a gelatino-silver-bromicdide developing-out emulsion, dye-sensitized as in Example 1, was added 4 hydroxy 3' acetyi 2 methylnaphtha- 1,2,4,5-thiazole, aminoguanide in a concentration of 100 mg. per that quantity of emulsion equivalent to 200 grams of silver nitrate. The resulting emulsion showed an increase in green sensitivity of per cent over the green sensitivity of Example 1. This increase in green sensitivity is apparent from Fig. 2 of the accompany drawing which depicts the sensitivity of the instant emulsion.

A gelatino-silver-bromiodide developing-out emulsion was sensitized with 3,3-diethyl0Xacarbocyanineiodide having the formula:

in a concentration equal to 100 mg. of the carbocyanine iodide per that quantity of emulsion equivalent to 200 grams of silver nitrate. The sensitizing effect of this quantity of dye is depicted in Fig. 4 of the accompanying drawing.

Example 5 To a gelatino-silver-bromiodide developing-out emulsion, dye-sensitized as in Example 3, was added l'- hydroxy 3'- acetyl-2-methylnaphtha- 1',2',4,5-thiazole semicarbazone in a concentration of 100 mg. per that quantity of emulsion equivalent to 200 grams of silver nitrate. The resulting emulsion showed an increase in green sensitivity of 30 per cent over the green sensitivity of Example 4. This increase'in' green sensitivity can be seen from Fig. 5 of the accompanying drawing which depicts the sensitivity of the instant emulsion.

In a manner similar to that illustrated in the foregoing examples, other 2'-cyanine dyes and oxacarbocyanine dyes can be supersensitized with one or more of the heterocyclic bases represented by the foregoing general formula:

My invention is primarily directed to the customarily employed gelatino-silver-halide developing-out emulsions, such as gelatino-silverchloride, gelatino-silver-chlorobromide, gelatinosilver-bromide and gelatino-silver-bromiodide emulsions.

Emulsions prepared in accordance with my invention can be coated in the usual manner upon any desired support, such as cellulose nitrate film, cellulose acetate film, polyvinyl acetal resin film, metal support, lass support or paper support.

The carbonylic compounds, such as 4'-hydroxy- 3'- acetyl 2 methylnaphtha 1',2',4,5 -thiazole, from which the compounds I employ in practicing my invention are prepared, are obtained as illustrated in the following example.

Example 6.4'-hydroa:y-3'acetyl-z-methylnaphtha-1',2',4,5thiazole V 4-phenyl-2-methylthiazole-5-acetic acid (11.66 grams) anhydrous sodium acetate (3 grams) and acetic anhydride (60 cc.) were refluxed gently for 3 hours. Acetic acid (10 cc.) was added and the mixture poured into water. The solid was collected and washed with water then a little methanol. On recrystallization from methanol,

5.8 grams of 4-acetoxy-2-methylnaphtha-1,2',-

Acidification with dilute acetic acid gave yellow flocks of 4'-hydroxy-3'-acetyI-Z-methylnaphthal',2',4,5thiazole which were recrystallized from methanol forming yellow needles M. P. 126 to 127 C. fiuorescing intensely green in ultraviolet light.

. (b) 4 hydroxy- 2 methylnaphtha -1',2',4,5- thiazole (0.5 gram), obtained above, was dissolved in nitrobenpene (5 cc.) with acetylchloride (0.2 gram) or aceticanhydride (0.3 gram). Aluminium chloride (1 gram) was then added at room temperature, then heated on the water bath for 4 hours. The deep yellow solution was decomposed with dilute hydrochloric acid forming yellow flocks. These were'collected, the nitrobenzene layer taken up in' ether, separated from the aqueous layer and extracted several times with I ZN-aqueous sodium'carbonate until the extracts were almost colorless. On neutralization with acetic acid; a further yield-of yellow flocks was given. Yield 0.35 gram. methanoLthey formed yellow needles M. P. 126 C; A mixed melting point with the product from '(a) showed no depression.

(c) 4:-acetoxy2emethylnaphtha-lf',2',4,5-thi-, azole (0.5 gram) in nitrobenzene (5 cc.) were Recrystallized from heated on the water bath for'4 hours with aluminium chloride (2 grams). On working up as usual 0.2 gram of the same product as from (a) was obtained.

Similarly other acyloxy compounds can be prepared using, propionic compounds, butyric compounds, etc., instead of acetic compounds.

The hydrazones,= semicarbazones, oximes and aminoguanides of the carbonylic compounds can be prepared by refluxing the carbonylic compound with a hydrazine salt, a semicarbazide salt, a hydroxylamine salt or an aminoguanidine salt in ethyl alcohol in the presence of sodium acetate.-

' Whatl claim as my invention and desire to be securedby Letters Patent of the United States is:

l. A photographic silver halide emulsion spectrally sensitized with at least one sensitizing dye selected from the group consisting of 2.-cyanine dyes and oxacarbocyanine dyes, said emulsion containing,v as a supersensitizer, at least one heterocyclic base selected from those represented -=by the following generalform l tizing dye selected from the group consisting of 2'-cyanine dyes and oxacarbocyanine dyes, said emulsion containing, as a supersensitizer, at least one heterocyclic base selected from those represented by the following general formula:

wherein R1 and R2 each represents an alkyl group and Z represents a hydrazono group, an alkylhydrazono group, a dialkylhydrazono group, an aralkylhydrazono group, a .diaralkylhydrazono group,xan arylhydrazono'group, a diarylhydrazono group, a carbamylhydrazono group, a thiocarbamylhydrazono group and a guanylhydrazono group.

3. A photographic gelatino-silver-halide developing-out emulsion spectrally sensitized with at least one sensitizing dye selected from the group consistingof 2'-cyanine dyes andoxacarbocyanine dyes, said emulsion containing, as a supersensitizer, at least one heterocyclic base selected from-those represented by the following general formula: g 1 1' wherein R1 and R2 each represents an alkyl group and Zrepresents a hydrazono group, an alkylhydrazono group, adialkylhydrazono group, an

'aralkylhydrazono group, a diaralkylhydrazono group, an arylhydrazono group, adiarylhydrazono group, acarbamylhydrazono group, athiocarbamylhydrazono' group and aguanylhydrazono 4. A photographic gelatino-silver bromiodide general formula:

7 oxacarbocyanine dyes, said emulsion containing, as a supersensitizer, at least one heterocyclic base selected from those represented by the following wherein R1 and R2 each represents an'alkyl group and Z represents a hydrazono group, an alkylhydrazono group, a dialkylhydrazono. group, an aralkylhydrazono group, a diaralkylhydrazono group, an arylhydrazonogroup, a diarylhydrazono 2 group, a carbamylhydrazono group, a thiocarbamylhydrazono group and a guanylhydrazono group.

5. A photographic igelatino-silyer-halide developing-rout emulsion spectrally sensitized with at least one 2'-cyanine sensitizing dye and containing, as a supersensitizer, at least one heterocyclic base selected from those represented by the following general formula:

wherein R-rand- R2 each represents an alkyl .group and Z represents a hydrazono group, an alkylhydrazono group, a dialkylhydrazono group, an aralkylhydrazono group, a diaralkylhydra zono group, an arylhydrazono group, a diarylhydrazono group, a oar-bamylhydrazonogroup, a thio- 'carb amy lhydrazono group and a' guanylhydrazono 6. A photographic gelatino-si1ver-bromiodide developing-out emulsion spectrally-sensitized with a t least one 2'-cyanine sensitizing .dye and containing, as a supersensitizer, at least one heterocyclic base selected from those represented :by he following general formula:

' wherein R1" and R2 each represents an alkyl group and Z represents a hydrazono group, an alkylhydrazono group, a dialk-ylhydrazono group, an aralkylhydraz'ono group, a diaralkylhydrazono group, an arylhydrazono group, a diarylhydrazono group, a carbamylhydrazono group, a thiccarbamylhydrazono group and a guanylhydrazono group.

7-...A photographic gelatinor silver-bromiodide .ideveloping-out emulsion spectrally sensitized -with-aat leastone Llt-xlialkykZBk-cyanlne salt 8 and containing, as a supersensitlzer, at least one heterocyclic base selected from, those represented by the: following; general vrormula:

wherein R1 and R2- each represents an alkyl group and Z. represents a hydrazono group, an alkylhydrazono group, a dialkylhydrazono group, an aralkylhydrazono group, a diaralkylhydrazono group, an .arylhydrazono group, a diarylhydrazono group, a carbamylhydrazono group, a thiocarbamylhydrazono group and .a guanylhydrazono. group.

9. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with at least one 3,1'-dialkylthia-2'-cyanine salt and containing, as a supersensitizer, at least one heterocyclic base selected from those represented by the. following general formula:

C-Ri

wherein R1 and R2- each represents an alkyl group and Z represents a hydrazono group, an alkylhydrazono "group, a diallgylhydrazono group, an aralkylhydrazono group, a diaralkylhydrazono group, an arylhydrazono group, a diarylhydr'a- "zono .group, a carbamylhydrazonov group, a thiocarbamylhydrazono group and a guanylhydrazono. group.

10. A photographic gelatino-silver-bronfiodide developing-out emulsion spectrally sensitized with at least :one l,l'-dialkyl-2,2'-cyanine salt in which the; slollhsgflgh. contain from selected from those represented by the following general formula:

wherein R1 and R2 each represents an alkyl group and Z represents a hydrazono group, an alkylhydrazono group, a dialkylhydrazono group, an aralkylhydrazono group, a diaralkylhydrazono group, an arylhydrazono group, a diarylhydrazono group, a carbamylhydrazono group, a thiocarbamylhydrazono group and a guanylhydrazono group.

12. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with at least one 3,1'-dialkylbenzothia-2-cyanine salt in which the alkyl groups each contains from 1 to 2 carbon atoms, the emulsion containing, as

10 a vsupersensitizer, at least one heterocyclic base selected from those represented by the following general formula:

wherein R1 and R2 each represents an alkyl group I and Z represents a hydrazono group, an alkylhydrazono group, a dialkylhydrazono group, an aralkylhydra'zono group, a diaralkylhydrazono group, an arylhydrazono group, a diarylhydrazono group, a carbamylhydrazono group, a thiocarbamylhydrazono group and a guanylhydrazono group.

13. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a 1,1-dialkyl-2,2-cyanine salt in which the alkyl groups each contains from 1 to 2 carbon atoms, the emulsion containing, as a supersensitizer, 4-hydroXy-3-acetyl-2-methylnaphtha-1, 2,4,5-thiazole semicarbazone.

14. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a 1,1-dialky1-2,2'-cyanine salt in which the alkyl groups each contains from 1 to 2 carbon atoms, the emulsion containing, as a supersensitizer, 4'- hydroxy-3'-acetyl 2 methylnaphtha-1',2,4,5- thiazole aminoguanide.

15. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a 1,1-diethyl-2,2-cyanine salt, the emulsion containing, as a supersensitizer, 4'-hydroxy-3- acety1-2 methylnaphtha- 1' ,2 ,4,5-thiazole semicarbazone.

16. A photographic gelatino-si1ver-bromiodide developing-out emulsion spectrally sensitized with a 1,1'-diethyl 2,2-cyanine salt, the emulsion containing, as a supersensitizer, 4'-hydroxy-3-acetyl 2 methylnaphtha-l',2,4,5-thiazole aminoguanide.

.17. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a 3-methyl-1-ethylthia-2-cyanine salt, the emulsion containing, as a supersensitizer, 4'-hy droxy-3'-acetyl-2-methylnaphtha 1,2',4,5-thiazole semicarbazone.

EDWARD B, KNOTT. 

